BACKGROUND OF THE INVENTION
Field of the Invention
[0001] This invention relates generally to a multi-v-ribbed power transmission belt, more
particularly to a v-ribbed belt having protruding fiber at a pulley-contacting surface,
and specifically to a belt having protruding deformable fibers which stand erect or
slightly bowed and which are deformed into an oval cross-sectional shape.
Description of the Prior Art
[0002] Power transmission belts such as v-belts, multi-v-ribbed belts and flat belts rely
on friction between a contact surface and a pulley or sheave to transmit power from
a driver sheave to the belt surface and thence to a driven sheave. A typical belt
construction includes a tensile member, an elastomeric belt body having discontinuous
synthetic thermoplastic and/or natural fibers embedded therein, and a pulley contact
surface. A rubber contact surface may generate a high friction coefficient and may
be associated with undesirable frictional noises. Exposure of the ends of the embedded
fibers at the contact surface may reduce the friction coefficient or otherwise control
friction and may alleviate some noise problems. Accordingly various configurations
of exposed fibers have been tried for example
US6482118.
[0003] Japanese Unexamined Patent Publication
H04-348930 discloses a method of polishing the surface of a rubber structure having short thermoplastic
fibers so as not to soften and melt the short fibers. The short fibers disclosed in
that publication are illustrated by fibers 1a in FIG. 1 which do not appear to protrude
more than about one fiber diameter. Disclosed as prior art in that publication are
similar fibers with melted ends as illustrated by fibers 1b in FIG. 1.
[0004] Japanese Unexamined Patent Publication
H05-8294 discloses as prior art nylon fiber ends that are round and have hardly come out from
the surface as illustrated by fiber 1c in FIG. 1. Also disclosed in that publication
is a rubber structure with meta-aramid staple fibers with a long extension from a
surface and lots of curl as illustrated by fibber 1d in FIG. 1, resulting in increased
fiber occupancy area and a surface with low coefficient of friction. Also disclosed
in that publication is a rubber structure with para-aramid or cotton staple fibers
with a short extension from a surface and split ends illustrated by fiber 1e in FIG.
1, resulting in a surface with high coefficient of friction.
[0005] U.S. Pat. No. 5,498,212 discloses a power transmission belt having embedded aramid fibers. The exposed ends
of para-aramid fibers are fibrillated and tend to curl as illustrated by fiber 1f
in FIG. 1.
[0006] US. Pat. No. 5,197,928 discloses a v-ribbed power transmission belt having embedded synthetic or natural
fibers. The exposed surface of the belt fibers is flared by melting or other method
so that its effective diameter is increased over the undeformed cross-sectional area
of the body of the fibers as illustrated by fiber 1g in FIG. 1.
[0007] U.S. Pat. No. 5,413,538 discloses a v-ribbed power transmission belt having synthetic or natural fibers embedded
in the belt body, no significant number of which project from the pulley-engaging
surface, and embedded aramid fibers which do project from the same surface. If any
non-aramid fibers project from the surface, it is characterized as stubble.
[0008] U.S. Pat. No. 5,904,630 discloses a machined, molded, ribbed, power transmission belt having embedded natural
or synthetic fibers. Surplus material 0.1 to 0.3 mm thick is machined from the ribs
so as to uncover protruding ends of the fibers. There is significant dispersion in
directions of the fibers.
[0009] U.S. Pat. No. 6,435,997 discloses a v-ribbed belt having synthetic fibers protruding from a rib face. The
extruded section of the fiber is plastically deformed in the shape of sectors gradually
broadened toward their distal ends as illustrated by fiber 1h in FIG. 1. The fiber
is kept unmelted and formed at its distal end in the shape of waves. The rib surface
has microscopic unevenness with a level difference of 0.5 to 10 µm as illustrated
by unevenness 1j in FIG. 1, and preferably with a wavy shape.
[0010] U.S. Pat. No. 6,695, 735 discloses a v-ribbed belt having short aramid fibers protruding from a rib face.
The root portions of the extruded short fibers are raised form the face, and the tip
portion is bowed in a different direction from its medial portion as illustrated by
fibers 1i in FIG. 1. The bowing directions of fibers differ from one another to decentralize
the orientation thereof.
[0011] U.S. Pat. No. 4,798,566 discloses a raw-edge power transmission belt having embedded discontinuous aramid
fibers with protruding portions bent against the elastomeric body portion of the belt
in such a manner as to expose lateral side portions of fiber which define part of
the friction driving surface as illustrated by fibers 1k in FIG. 1. Most of the aramid
fibers protrude from 0.1 to 0.3 mm.
SUMMARY
[0012] The present invention is directed to a power transmission belt with embedded deformable
fibers having an embedded cross-sectional shape that is substantially undeformed from
the fiber's original shape, while the protruding fiber is substantially erect with
respect to the contact surface or slightly bowed, and along substantially all the
protruding length the protruding fiber is deformed from the original cross-sectional
shape to an elongated, oval, or flattened shape.
[0013] The present invention is directed to a power transmission belt having a tensile member,
an elastomeric belt body having a plurality of discontinuous fibers embedded therein,
and a pulley contact surface as defined by claim 1. Each embedded fiber has an embedded
cross-sectional shape that is substantially undeformed from its original cross-sectional
shape and characterized by an average fiber diameter, and a plurality of fiber ends
protrude from the contact surface with a protruding length and a protruding cross-sectional
shape. The fibers comprise deformable polymeric material. The fibers may be of thermoplastic
or thermally deformable polymer, whether synthetic or natural. A plurality of protruding
fiber ends are substantially erect with respect to the contact surface, substantially
straight or slightly bowed, and substantially uniformly deformed from the original
cross-sectional shape along most of the protruding length.
[0014] The protruding length of the fibers may be at least 2 average fiber diameters, or
from about 5 to about 20 average fiber diameters, or from about 0.1 to about 0.6 mm,
or from 0.15 to about 0.3, or at least about 0.2 mm or more.
[0015] In various embodiments of the present invention, the plurality of protruding fiber
ends may be deformed from a substantially round original cross-sectional shape to
one or more of an oval, kidney, oblong, semicircular, and flattened circle cross-sectional
shape. In other embodiments, protruding fiber portions may be deformed from an original
oval or dumbbell shape to a flattened or more elongated oval or dumbbell shape.
[0016] The discontinuous fibers may have an average length from about 0.5 to about 5 mm,
or an average length of about 1 to about 3 mm. The discontinuous fibers may have an
average diameter, or if not round, an average major dimension, of about 10 to about
50 microns, or from about 15 or about 20 to about 30 microns.
[0017] The deformable fiber may be one or more selected from the group consisting of nylon,
acrylic, polyester, polyketone, polyolefin, and meta-aramid. The deformable fiber
may be a thermally deformable synthetic thermoplastic polymer fiber. The deformable
fiber may have a softening point of greater than about 100°C, or greater than about
180°C, or from about 190°C to about 350°C.
[0018] The deformed cross-sectional shape of the protruding portions of the fibers may be
characterized by a ratio of a major dimension to a minor dimension in the range from
1.1 or 1.2 to about 5, or from about 2 to about 3, or may be characterized by deformation
from a circular diameter by factors of about 1.33 and about 0.67 for the major and
minor dimensions respectively. In various embodiments of the present invention, the
deformation of the protruding fiber cross-sectional shape may be characterized by
a major dimension that is elongated from the original shape by about 10% to about
100%, or from about 20% to about 50%, or about 30%.
[0019] The elastomeric belt body may be of one or more of EPDM, EPM, SBR, NR, BR, CR, NBR,
HNBR, ethylene-alpha-olefin elastomer, and the like.
[0020] The average surface roughness of the contact surface may be more than 10 microns,
preferably more than 20 microns, or about 50 microns and irregular.
[0021] The amount of embedded fiber in the elastomeric belt body may be from about 1 to
about 50 phr, or about 5 to about 30 phr, based on 100 parts of elastomer. The number
of exposed fibers on the contact surface may be in the range from 20 to 150 fibers
per mm
2 or 50 to 100 fibers per mm
2, or about 75 fibers/mm
2.
[0022] The fibers may be bent at the roots so that at least a portion of the protruding
portions lie substantially parallel to the rubber surface or even touching the rubber
surface. At least some of the bent fibers may have a substantially erect portion at
the free end.
[0023] The foregoing has outlined rather broadly the features and technical advantages of
the present invention in order that the detailed description of the invention that
follows may be better understood. Additional features and advantages of the invention
will be described hereinafter which form the subject of the claims of the invention.
It should be appreciated by those skilled in the art that the conception and specific
embodiment disclosed may be readily utilized as a basis for modifying or designing
other structures for carrying out the same purposes of the present invention. It should
also be realized by those skilled in the art that such equivalent constructions do
not depart from the scope of the invention as set forth in the appended claims. The
novel features which are believed to be characteristic of the invention, both as to
its organization and method of operation, together with further objects and advantages
will be better understood from the following description when considered in connection
with the accompanying figures. It is to be expressly understood, however, that each
of the figures is provided for the purpose of illustration and description only and
is not intended as a definition of the limits of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The accompanying drawings, which are incorporated in and form part of the specification
in which like numerals designate like parts, illustrate embodiments of the present
invention and together with the description, serve to explain the principles of the
invention. In the drawings:
FIG. 1 is a fragmented sectional diagram of various prior art fiber configurations.
FIG. 2 is a sectional diagram of a portion of a multi-V-ribbed belt constructed in
accordance with an embodiment of the present invention;
FIG. 3 is a magnified sectional view of a portion of the belt of FIG. 2;
FIG. 4 is a partially fragmented perspective view of a portion of a belt constructed
in accordance with an embodiment of the present invention;
FIG's 4A-4F are cross-sections of exposed fiber according to embodiments of the present
invention;
FIG. 5 is a partially fragmented perspective view of a portion of a belt constructed
in accordance with an embodiment of the present invention; and
FIG. 6 is a fragmented sectional diagram of exposed fiber configurations according
to embodiments of the invention.
DETAILED DESCRIPTION
[0025] Referring to FIG. 2, a power transmission belt in the form of multi-V-ribbed belt
10 in accordance with an embodiment of the present invention is shown generally. Multi-V-ribbed
belt 10 includes at least one longitudinally extending tensile member or load-carrying
cord 14 positioned below overcord layer 12 on the back side of the belt and above
elastomeric main belt body portion 18, also known as the undercord layer. The tensile
member may be at least partially in contact with or embedded in adhesive rubber member
16 which is frequently visually indistinguishable from the surrounding elastomeric
belt body portion except in cases, e.g., where one and not the other of adhesive rubber
member 16 and undercord 18 is fiber loaded. Main belt body portion 18 includes rib
19 and sheave or pulley contact surface 20. The word, "sheave" as used in this context
includes conventional pulleys and sprockets used with a power transmission belt, and
also rollers and like mechanisms. The particular sheave contact portion of the belt
of FIG. 2 is in the form of a plurality of ribs 19 having there between oppositely
facing sides 20a and 20b. Sheave contact portion 20 is integral with rib 19 and main
belt body portion 18 and may be formed from the same elastomeric, fiber-loaded material(s)
as described below. Adhesive rubber member 16 around cord 14, overcord 12, undercord
18, and/or rib 19 may actually be of the same material, or they may be of different
materials. At least a portion of rib 19 and contact portion 20 comprise a plurality
of embedded short or discontinuous fibers 22, at least some of which have protruding
portions 24 which protrude from contact portion 20.
[0026] FIG. 3 shows a magnified portion of two ribs 19 with embedded fibers 22 and protruding
fiber portions 24 from pulley contact surfaces 20a and 20b according to an embodiment
of the invention. Each embedded fiber has an embedded cross-sectional shape that is
undeformed from its original shape and characterized by an average fiber diameter
and/or major and minor dimensions, and a plurality of fiber ends protrude from the
contact surface with a protruding length and a protruding cross-sectional shape. Many
or most of the protruding fiber ends 24 are substantially erect with respect to the
contact surface, and substantially straight or slightly bowed. In other words, most
of the protruding fibers are not bent at or near the roots, so they stand substantially
erect with respect to the elastomeric surface from which they protrude. If protruding
fibers are bowed, the bow is generally in the longitudinal direction of the belt,
and the bow is generally unidirectional. Generally the longer the protruding portion,
the more bow may be exhibited. The protruding fiber ends are not split, and the protruding
fibers are not splayed or melted or flared, but are of relatively uniform cross-section
along substantially all the protruding length.
[0027] FIG. 4 shows a greatly magnified view of a portion of single protruding fiber 24
and a portion of embedded fiber 22. Embedded fiber 22 and the embedded portion of
protruding fiber 24 have a substantially round cross-sectional shape with average
diameter "D" as shown in the sectional view of FIG 4A. Protruding fiber portion 24
has protruding length "H" and is deformed from the round cross-sectional shape of
the embedded fibers and embedded portions of protruding fibers along most of its protruding
length. The deformation of portion 24 may be substantially uniform along most or substantially
all of its protruding length. In various embodiments of the present invention, the
protruding fiber ends may be deformed from the substantially round shape to one or
more of an oval, kidney, oblong, semicircular, and flattened circle cross-sectional
shape. An example oval cross-sectional shape is shown in FIG. 4D. By oval is meant
generally any deviation from circular including oblong, elliptical, egg-shaped, kidney-shaped,
dumbbell-shaped, or the like, whether symmetrical or not. What is not meant by oval
is a very flat, thin, film-like shape. An example kidney cross-sectional shape is
shown in FIG. 4B. Kidney shape may include shapes with a convex portion and a concave
portion. An example oblong cross-sectional shape is shown in FIG. 4C. Oblong is not
used herein in a precise sense, but is generally suggestive of an oval shape that
is longer and thinner, and/or more deformed from circular, than other, more typical
oval shapes. FIG. 4E shows an example of a flattened circular cross-sectional shape.
Though shown in FIG. 4E with sharp corners, a flattened circular shape may have somewhat
rounded corners according to an embodiment of the invention. Finally, FIG. 4F shows
an example of a dumbbell shape, which may be considered to be like a kidney shape,
but with two concave sides, or like a peanut shape. FIG. 4F may also be considered
a two-lobed example of a more general class of multi-lobed shapes. In each case, the
deformed cross-sectional shape of the protruding fiber may thus have a major or larger
dimension and a minor or smaller dimension. In FIG. 4B, for example, the major dimension
is indicated as "L" and the minor dimension as "W". The deformed cross-sectional shape
of the protruding portions of the fibers may thus be characterized by a ratio of a
major dimension to a minor dimension, or L/W. In preferred embodiments of the invention,
the cross-sectional shape of the protruding portion may have a ratio, L/W, in the
range from about 1.1 to about 5, or in the range from about 1.2 to about 5, or the
ratio may in the range from about 2 to about 3. Alternately, the cross-sectional shape
of the protruding portion may be characterized by an amount of deviation from an original
circular diameter exhibited by the major and minor dimensions, i.e. L/D and W/D, respectively.
In preferred embodiments of the invention, the cross-sectional shape may be characterized
by factors of about 1.33 and about 0.67 for L/D and W/D, respectively.
[0028] Alternately, embodiments of the invention may be characterized by an original non-circular
shape having a major dimension and minor dimension, such as indicated in FIG. 4B.
For such non-round fibers, the deformation of the protruding fiber ends may more conveniently
be characterized by percent elongation of the major dimension. Thus, a major dimension
of the protruding cross-sectional shape may preferably be elongated from that of the
original shape by from about 5% or 10% to about 100%, or about 30%. An example of
such a non-round fiber is Nomex meta-aramid fiber, which has a two-lobed or dumbbell
cross-sectional shape as illustrated in FIG. 4F. It has been found that belts with
exposed Nomex fiber at a contact surface having a major dimension ranging from 5%
to 20% greater than the original shape have excellent noise performance and durability
in belt testing. FIG. 5 illustrates a protruding fiber 50 of original two-lobe- or
dumbbell-shaped cross section 52.
[0029] Without intent to limit the invention, it is believed that the advantage of an elongated
or oval cross-sectional shape is that the exposed surface area of the fiber can be
increased without significant accompanying decrease in fiber strength or durability.
The length of the protruding fiber can be maximized without a decrease in strength
or durability of the fiber. The combination of maximized protruding length and somewhat
increased major cross-sectional dimension results in a large increase of exposed surface
area for a given amount of fiber in the elastomer composition. This may be advantageous
because increasing the amount of fiber too much in an attempt to increase exposed
fiber surface can have detrimental effects on other properties of the rubber. Likewise,
increasing fiber exposed surface area of fiber by splaying or making the fibers too
thin can have detrimental effects on fiber wear resistance, strength, or other properties
of the surface fiber. Increased exposed fiber surface area as contemplated by the
present invention may be advantageous for control of noise and frictional characteristics
of the belt contact surface, without some of the detrimental effects of prior art
methods.
[0030] It is believed that belts according to embodiments of the present invention initially
run very quiet with the cushioning effect of the erect protruding fibers. Moreover,
it is believed these belts continue to run quiet because of the thickness of fiber
material between pulley and rubber surface, even if the fibers become bent over onto
the rubber surface due to some handling or processing or during use. It is believed
that the erect fibers of embodiments of the present invention generally bend over
in use, laying on the rubber contact surface in substantially parallel and unidirectional
fashion, although some fiber crossing may also occur. Thus, while the contact surface
is herein referred to as an elastomeric or rubber surface of the belt body, the protruding
fibers actually make up perhaps a more significant aspect of the contact surface.
Rubber itself generally has very high friction coefficient relative to fibers. In
embodiments of the present invention, bent over fibers of sufficient thickness, length,
and density reside between, and prevent direct contact between, the rubber portion
of the contact surface and a pulley or sheave surface. Also, a series of oval or rounded
fibers may present a relatively rough friction surface, which has also been found
favorable for reducing noise. Moreover, the thickness of the fibers makes them strong,
durable, and/or resistant to abrasive wear. In contrast, prior art fibers may be too
short, splayed, fibrillated and/or made too thin or flat to have long lasting resistance
to abrasive wear or to prevent contact between rubber surfaces and pulley surfaces
or to present a very rough contact surface.
[0031] The protruding length "H" of the fibers may be at least 2 fiber diameters, or from
about 5 to about 20 fiber diameters, or from about 0.1 to about 0.5 mm, or from about
0.2 mm to about 0.3 mm. Generally, the longer the protruding portions of the fibers,
the better the belt performance as described below. However, the maximum protruding
length attainable may be limited by practical considerations. For example, if insufficient
portions of fiber remain embedded in the belt body, then the fiber will most likely
pull out of the contact surface and make no contribution to belt performance. In one
embodiment, it has been observed that 1-mm long nylon fibers may protrude a maximum
of about 0.4 mm, or about half the fiber length, before fiber pull-out becomes a significant
problem. Pull-out may also be affected by adhesion or lack thereof between fiber and
elastomer composition.
[0032] The discontinuous fibers may have an average length from about 0.5 to about 5 mm,
or an average length of about 1 mm to about 3 mm. The discontinuous fibers may have
an original average diameter of about 10 microns to about 50 microns, or an average
diameter of about 20 microns to about 30 microns. Fibers of non-circular cross-sectional
shape may preferably have an original major dimension of about 10 microns to about
50 microns, or from about 15 microns to about 30 microns.
[0033] The deformable fiber may be one or more selected from the group consisting of nylon,
acrylic, polyester, polyolefin, polyketone, and meta-aramid. The deformable fiber
may be a thermally deformable synthetic thermoplastic polymer fiber. The deformable
fiber may have a softening point of greater than about 100°C, or greater than about
190°C, or from about 180°C to about 350°C. The deformable fiber need not have a true
melting point, as long as some softening accompanied by thermal deformation is possible
to produce the required deformation in cross-sectional shape of the fiber.
[0034] Examples of useful fibers for embodiments of the present invention include: nylon-66
with softening point of about 240°C; nylon-6 with softening point of about 180°C;
Nylon-46 with softening point of about 260-270°C; polyester with softening point of
about 255°C; Nomex® meta-aramid sold by DuPont or TeijinConex meta-aramid sold by
Teijin Ltd. with softening point of about 280°C; and acrylic with softening point
of about 240°C, or the like. A preferred fiber is nylon, including nylon-66, nylon-6,
and/or nylon-46. The fibers may be medium or high-tenacity nylon. Fibers may include
oxidative or heat stabilizers, lubricants, or other minor additives. Fibers may be
treated with resorcinol-formaldehyde-latex (RFL), isocyanate, or other adhesive treatment
to improve adhesion and reduce pull-out during profile processing or subsequent use.
Acrylic is an example of a useful fiber which is considered to decompose before melting,
yet considered to soften before decomposition occurs and thus be thermally deformable.
Polyacrylonitrile ("PAN") fibers are sold, for example, by Toyobo Co. Ltd. PAN fibers
include fibers with a range of acrylic content, generally at least 85% acrylonitrile,
and various comonomers, such as methyl methacrylate, vinyl acetate, and the like.
Nomex meta-aramid also has a softening point or at least a point at which some thermal
deformation is possible. Olefin fibers include polyethylene, ultra-high molecular
weight polyethylene, polypropylene, and the like. Polyketones include polyetherketones
(PEK), polyetheretherketones (PEEK), polyetherketoneketones (PEKK), and polyaryletherketones
(PAEK), polyolefin ketone (POK), and the like, (collectively "PK"). Polyesters include
polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and the like. PEN
is sold under the trademark PENTEX by Honeywell International Inc. PEN is also sold
by Teijin Limited, INVISTA, and Hyosung Corporation. It is believed para-aramid fibers
are not sufficiently thermally deformable to be practical in carrying out the present
invention, although some mechanical deformation may be possible with some advantageous
effect.
[0035] The rubber or elastomeric material of the surface may present a smooth surface from
which fibers protrude. Alternately, as shown in FIG. 5, surface 20 may have irregular
peaks 36 and valleys 38, resulting in an average roughness characterized by an average
height difference "R". The average surface roughness of the contact surface may advantageously
be more than 10 microns, preferably from about 20 to about 100 microns, or about 50
microns, and irregular. It is believed that such roughness and/or irregularity contributes
to the ability of the belt to run quietly in a sheave. It is hypothesized that the
roughness and irregularity of the surface serves to support or elevate above the surface
any fibers which are bent as described above and thereby to further prevent noise-producing
contact between a pulley and the rubber surface.
[0036] The elastomeric belt body may include one or more elastomeric formulations based
on one or more of ethylene-propylene elastomers (EPDM, EPM, and the like), styrene-butadiene
rubber (SBR), chloroprene (CR), natural rubber (NR), butyl rubber (BR), nitrile (NBR),
hydrogenated nitrile (HNBR), ethylene-alpha-olefin elastomer, or the like. Each elastomeric
formulation may include one or more of plasticizers, reinforcing fillers including
additional natural or synthetic short fibers, extenders, antioxidants, antiozonants,
process aids, adhesion promoters, accelerators, coagents, curatives, and the like.
[0037] The amount of embedded short or discontinuous fiber in the elastomeric belt body
may be from about 1 to about 50 phr, or about 5 to about 30 phr, based on 100 parts
of elastomer. The number of exposed fibers on the contact surface may advantageously
be in the range from 20 to 150 fibers per mm
2, or from 50 to 100 fibers per mm
2, or about 75 fibers/mm
2.
[0038] FIG. 5 illustrates some of the variety of fiber ends protruding from rubber surface
20 that may by included in embodiments of the present invention. As mentioned above,
non-circular fiber 50 has a dumbbell shaped cross section 52. The other fibers illustrated
in FIG. 5 have originally round cross-sections like the embedded fiber 22. Fiber 23
does not protrude as much as preferred, but may be just enough, at an H/D ratio of
about 2 or a couple fiber diameters, to have a positive effect on belt performance.
Fiber 34 protrudes an amount indicated by height "H", which is several times a fiber
diameter. Fiber 34 also has an oval cross section 29 and substantially uniform cross
section along most of the protruding length. Fiber 30 is substantially erect, has
a greater protruding length than fiber 34, and is slightly bowed near the exposed
end. Fiber 30 has deformed oval cross section 28. Fiber 25 protrudes even farther
than fiber 30 resulting in a little more bowing near fiber end 40. Fiber 25 also has
a substantially uniform flattened circular cross section 32. Hole 26 indicates a round
fiber was pulled out of the rubber.
[0039] FIG. 6 illustrates other fiber forms or protruding fiber configurations according
to another embodiment of the invention. FIG. 6 shows bent fibers 54 parallel to or
touching surface 20. Fibers 54 are bent at root 56, have parallel or touching section
58, and end with a substantially erect portion 60 at the free end. Preferably, erect
portion 60 is at least as long as two times the average fiber diameter. In other aspects,
not shown, the fibers may have the same kinds of features described above, including
substantially uniform deformed cross sections in the protruding length. The fibers
may be bent as a result of manufacturing conditions, or post-manufacturing use or
handling. FIG. 6 also illustrates how one or more high spots 36 on rubber surface
20 may support fiber 54, as suggested above. It should be noted that with further
use or processing, erect portions 60 may also be forced down parallel to surface 20.
[0040] A reinforcing fabric (not shown in FIG. 1) may optionally be utilized and in the
case of V-belts and multi-V-ribbed belts intimately fits along the top surface of
a belt to form a face cover or overcord 12 for the belt. The fabric may be of any
desired configuration such as a conventional weave consisting of warp and weft threads
at any desired angle, or may consist of warp threads held together by spaced pick
cords as exemplified by tire cord fabric, or of a knitted or braided configuration,
or of a nonwoven configuration, or paper, or plastic film, and the like. The fabric
may be friction- or skim-coated with the same or different elastomer composition as
that of elastomeric main belt body 18. More than one ply of fabric may be employed.
If desired, the fabric may be cut or otherwise formed to be arranged on a bias so
that the strands form an angle with the direction of travel of the belt. A fabric
layer may reside between cord 14 and overcord 12.
[0041] Embodiments of the present invention may be made according to methods known in the
belt-manufacturing arts. For example, a slab may be built up inverted on a mandrel
by applying to the mandrel overcord, helically wound cord, and undercord. The slab
may be cured by applying external pressure through a flexible sleeve. Individual belts
may be cut from the sleeve and profiled using grinders and/or cutters which form the
pulley contact surface and expose embedded short fibers so that portions of at least
some fibers protrude from the contact surface according to an embodiment of the present
invention. A grinding process is disclosed for example in each of
U.S. Pat. Nos. 4,956,036 and
6,764,382. A cutting process is disclosed for example in
U.S. Pat. Publication No. 2006/0236839. The deformation of the protruding fibers of embodiments of the present invention
may best be obtained by allowing the grinding or cutting tool to heat the belt contact
surface to and/or the tool itself to just a temperature at which the fibers soften
enough to deform, but no hotter. The resulting deformed fiber generally has a smooth
surface appearance. If the temperature or heat generated by grinding or cutting is
excessive, the softened fibers will be weakened, cut off too short, splayed or flared,
and/or deformed excessively, for example into a thin ribbon configuration. If the
temperature or heat generated is insufficient and does not soften the fibers, the
fibers may be mechanically roughened, abraded, cut short, or split and flared. Cutting
processes may generally run cooler than grinding processes, although either process
can be controlled over a fairly broad temperature range by adjusting tool rotational
speeds, feed rates, grit density, and the like as known in the art. In addition, various
external cooling methods may be used to control the process temperature, including
for example, liquid nitrogen, cold air gun or blower, water spray, and the like.
[0042] Example multi-v-ribbed belts (indicated by "Ex." and a number) according to embodiments
of the invention were constructed and tested to demonstrate the usefulness and advantages
of the present invention. For comparison, comparative examples (indicated by "Comp.
Ex." and a letter) were also constructed. All belts had polyester cord and EPDM elastomer
belt body like the examples of
U.S. Pat. No. 5,610, 217 and could be described as 6PK1200. The belts, however, had either 25 parts per hundred
parts of elastomer ("phr") of chopped nylon-66 fibers of average length 1 mm, or 6
phr of chopped Nomex fibers of average length 1.5 mm. The elastomer recipe had a total
of about 200 parts. The nylon fibers were also round with original average diameter
of either 20 microns or 30 microns as indicated in Table 1. The Nomex fibers were
not round, having a dual-lobed shape as illustrated in FIG. 4F and fiber 50 in FIG.
5. The example belts had a rib profile produced by cutting, with protruding fiber
portions as shown in FIG. 2, 3, and 5, and having typical deformed dimensions as indicated
in Table 1. The comparative examples had rib profiles produced by grinding, with protruding
fiber configurations similar to fibers 1c, 1e, 1g, and/or 1h in FIG. 1, predominantly
flared, thin fibers similar to 1h, and typical dimensions as indicated in Table 1.
The typical dimensions were obtained by selecting a typical-looking fiber from low-magnification
SEM micrographs and measuring the dimensions of that fiber from a high-magnification
SEM micrograph. When a range of dimensions is indicated in Table 1, the variation
observed in the specimens was significant. It should be noted that determining the
W dimension was the most difficult, especially for very thin Comp. Ex's. Therefore,
the L/D measurement may be a more accurate indication of the fiber deformation. The
% elongation was simply calculated from L/D in Table 1.
[0043] The example belts were tested to demonstrate the utility and durability and performance
advantages of embodiments of the present invention. Durability analysis involved running
test belts on a five-point flex life test and a heated, load and flex life test. All
belts passed the durability analysis. Noise tests involved running belts on misaligned
pulleys under both wet and dry conditions. Initial tests were run on newly made belts,
which, in the case of the example belts, had substantially erect protruding fibers
according to embodiments of the invention. Conditioned tests involved the same noise
testing as the initial tests, but after conditioning the belts for 96 hours on the
above-mentioned heated, load and flex life tester. Thus, the conditioned example belts
had protruding fibers that were bent over toward the rubber surface. While all belts
ran quietly for the initial noise testing and for the dry noise testing after conditioning,
only the example belts ran quietly in wet noise tests after conditioning. Thus, embodiments
of the invention exhibit durability and quiet operation in a variety of conditions
and over a long period of use.
[0044] Other embodiments of the present invention may be envisioned. For example, multi-lobed
thermally deformable fibers may be used, such as three-lobed polyimide or polyamide-imide
fibers including P84 fibers sold under that trade name by Inspec Fibres, a Degussa
company.
Table 1.
Belt Examples |
Ex. 1 |
Comp. Ex. A |
Ex. 2a |
Ex. 2b |
Comp. Ex. B |
Ex. 3 |
Fiber type |
nylon-66 |
nylon-66 |
nylon-66 |
nylon-66 |
nylon-66 |
Nomex |
Fiber D (µm) |
20 |
20 |
30 |
30 |
30 |
16-21 |
Fiber length (mm) |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
1.5 |
Profile process |
cutting |
Grinding |
cutting |
cutting |
grinding |
cutting |
Fiber shape |
FIG's 2-4 |
∼FIG. 1h |
FIG's 2-4 |
FIG's 2-4 |
∼FIG. 1h |
FIG. 5 (50) |
Length H (mm) |
0.05-0.20 |
0.05-0.10 |
0.10-0.45 |
0.05-0.25 |
0.10-0.20 |
0.05-0.30 |
H / D |
2.5-10 |
2.0-5 |
3.0-15 |
3.0-10 |
5 |
10 |
L / W |
4.0 |
10 |
2 |
2.5 |
7-20 |
2.0-5.0 |
L / D |
1.8 |
2.5 |
1.3 |
1.5 |
3.0 |
1.1-2.0 |
% elongation |
80% |
150% |
30% |
50% |
200% |
10-100% |
Durability analysis |
pass |
Pass |
pass |
pass |
pass |
pass |
Initial Noise - Dry |
quiet |
Quiet |
quiet |
quiet |
quiet |
quiet |
Initial Noise - Wet |
quiet |
Quiet |
quiet |
quiet |
quiet |
quiet |
Conditioned Noise - Dry |
quiet |
Quiet |
quiet |
quiet |
quiet |
quiet |
Conditioned Noise - Wet |
quiet |
Chirp |
quiet |
quiet |
chirp |
quiet |
[0045] Although the present invention and its advantages have been described in detail,
it should be understood that various changes, substitutions, and alterations can be
made herein without departing from the scope of the invention as defined by the appended
claims. Moreover, the scope of the present application is not intended to be limited
to the particular embodiments of the process, machine, manufacture, composition of
matter, means, methods, and steps described in the specification. As one of ordinary
skill in the art will readily appreciate from the disclosure of the present invention,
processes, machines, manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed that perform substantially the same function
or achieve substantially the same result as the corresponding embodiments described
herein may be utilized according to the present invention. Accordingly, the appended
claims are intended to include within their scope such processes, machines, manufacture,
compositions of matter, means, methods, or steps. The invention disclosed herein may
suitably be practiced in the absence of any element that is not specifically disclosed
herein.
1. A power transmission belt (10) comprising a tensile member (14), an elastomeric belt
body (18) having a plurality of discontinuous deformable fibers (22) embedded therein,
and a pulley contact surface (20);
with each said fiber (22) having an original average fiber diameter and having an
original cross-sectional shape that is substantially unchanged for embedded portions
of the fiber (22); and
with a plurality of fiber ends (24) protruding substantially erect from said contact
surface (20) and substantially straight or slightly bowed and having a protruding
length and characterised by having a protruding cross-sectional shape that is substantially uniformly deformed
from the original cross-sectional shape along most of the protruding length resulting
in protruding fibers of uniform cross-section along all the protruding length.
2. The belt (10) of claim 1 wherein the original shape is substantially round and the
plurality of protruding fiber ends (24) are deformed from the round shape to one or
more of an oval, kidney, oblong, semicircular, and flattened circle cross-sectional
shape.
3. The belt (10) of claim 1 wherein the original shape is oval or dumbbell shaped and
the protruding cross-sectional shape is deformed to a flattened or more elongated
oval or dumbbell shape.
4. The belt (10) of claim 1 wherein the discontinuous fibers (22) have an average length
of from about 0.5 to about 5 mm, and an original average diameter of from about 10
microns to about 50 microns.
5. The belt (10) of claim 1 wherein the discontinuous fibers (22) have an average length
of from about 1 mm to about 3 mm, and an original average diameter of from about 20
microns to about 30 microns.
6. The belt (10) of claim 1 wherein said protruding length is at least 2 original average
fiber diameters.
7. The belt (10) of claim 1 wherein said protruding length is from about 5 to about 20
fiber diameters.
8. The belt (10) of claim 1 wherein said deformable fiber (22) is one or more selected
from the group consisting of nylon-6, nylon-46, nylon-66, acrylic, polyester, polyketone,
polyolefin, and meta-aramid.
9. The belt (10) of claim 1 wherein the deformable fiber (22) has a softening point of
greater than about 100°C.
10. The belt (10) of claim 1 wherein said deformable fiber (22) is nylon or meta-aramid.
11. The belt (10) of claim 1 wherein said fiber deformation is characterized by a ratio of a major dimension to a minor dimension in the range from about 1.2 to
about 5, or characterized by deformation from circular by a factor of about 1.33 and 0.67 for the two axes respectively.
12. The belt (10) of claim 1 wherein said fiber deformation is characterized by a major dimension that is elongated by from about 10% to about 100%.
13. The belt (10) of claim 1 wherein the average surface roughness of the contact surface
(20) is more than about 20 microns and irregular.
14. The belt (10) of claim 1 wherein the amount of said fiber (22) in said elastomeric
belt body (18) is from about 1-50 phr based on 100 parts of elastomer.
15. The belt (10) of claim 1 wherein the number of exposed fibers (22) on the contact
surface (20) is in the range from 20 to 150 fibers per mm2.
16. The belt (10) of claim 1 wherein most of the protruding fibers (22) are bent at the
roots with at least a portion of the protruding portions substantially parallel to
and very close to or touching the contact surface.
17. The belt (10) of claim 16 wherein at least some of the bent protruding fibers (22)
have a substantially erect portion at the free end.
1. Kraftübertragungsband (10), umfassend ein Zugteil (14), einen elastomeren Bandkörper
(18), der mehrere diskontinuierliche, verformbare Fasern (22) darin eingebettet aufweist,
und eine Rollenkontaktfläche (20);
wobei jede Faser (22) einen ursprünglichen durchschnittlichen Faserdurchmesser und
eine ursprüngliche Querschnittsgestalt aufweist, die im Wesentlichen bei den eingebetteten
Abschnitten der Faser (22) unverändert ist; und
wobei mehrere Faserenden (24) im Wesentlichen aufrecht von der Kontaktfläche (20)
und im Wesentlichen gerade oder leicht gebogen hervorstehen und eine hervorstehende
Länge aufweisen, dadurch gekennzeichnet, dass sie eine hervorstehende Querschnittsgestalt aufweisen, die im Wesentlichen gleichförmig
von der ursprünglichen Querschnittsgestalt dem größten Teil der hervorstehenden Länge
entlang verformt ist, was zu hervorstehenden Fasern von gleichförmigem Querschnitt
der gesamten hervorstehenden Länge entlang führt.
2. Band (10) nach Anspruch 1, wobei die ursprüngliche Gestalt im Wesentlichen rund ist
und die mehreren hervorstehenden Faserenden (24) von der runden Gestalt zu einer ovalen,
nierenförmigen, länglichen, halbrunden und/oder abgeflachten kreisförmigen Querschnittsgestalt
verformt sind.
3. Band (10) nach Anspruch 1, wobei die ursprüngliche Gestalt oval oder hantelförmig
ist und die hervorstehende Querschnittsgestalt zu einer abgeflachten oder länglicheren
ovalen oder hantelförmigen Gestalt verformt ist.
4. Band (10) nach Anspruch 1, wobei die diskontinuierlichen Fasern (22) eine durchschnittliche
Länge von etwa 0,5 bis etwa 5 mm und einen ursprünglichen durchschnittlichen Durchmesser
von etwa 10 Mikron bis etwa 50 Mikron aufweisen.
5. Band (10) nach Anspruch 1, wobei die diskontinuierlichen Fasern (22) eine durchschnittliche
Länge von etwa 1 mm bis etwa 3 mm und einen ursprünglichen durchschnittlichen Durchmesser
von etwa 20 Mikron bis etwa 30 Mikron aufweisen.
6. Band (10) nach Anspruch 1, wobei die hervorstehende Länge mindestens 2 ursprüngliche
durchschnittliche Faserdurchmesser beträgt.
7. Band (10) nach Anspruch 1, wobei die hervorstehende Länge etwa 5 bis etwa 20 Faserdurchmesser
beträgt.
8. Band (10) nach Anspruch 1, wobei die verformbare Faser (22) eine oder mehrere Alternativen
aus der Gruppe bestehend aus Nylon 6, Nylon 46, Nylon 66, Acryl, Polyester, Polyketon,
Polyolefin und MetaAramid ist.
9. Band (10) nach Anspruch 1, wobei die verformbare Faser (22) einen Erweichungspunkt
von mehr als etwa 100 °C aufweist.
10. Band (10) nach Anspruch 1, wobei die verformbare Faser (22) Nylon oder Meta-Aramid
ist.
11. Band (10) nach Anspruch 1, wobei die Faserverformung durch ein Verhältnis einer Hauptdimension
zu einer geringeren Dimension im Bereich von etwa 1,2 bis etwa 5 gekennzeichnet ist
oder durch Verformung von kreisförmig um einen Faktor von etwa 1,33 bzw. 0,67 für
die beiden Achsen gekennzeichnet ist.
12. Band (10) nach Anspruch 1, wobei die Faserverformung durch eine Hauptdimension gekennzeichnet
ist, die um etwa 10 % bis etwa 100 % verlängert ist.
13. Band (10) nach Anspruch 1, wobei die durchschnittliche Oberflächenrauheit der Kontaktfläche
(20) mehr als etwa 20 Mikron und unregelmäßig ist.
14. Band (10) nach Anspruch 1, wobei die Menge der Faser (22) in dem elastomeren Bandkörper
(18) etwa 1 - 50 Teile pro hundert Teile (phr), auf 100 Teile Elastomer bezogen, beträgt.
15. Band (10) nach Anspruch 1, wobei die Anzahl bloßgelegter Fasern (22) auf der Kontaktfläche
(20) im Bereich von 20 bis 150 Fasern pro mm2 liegt.
16. Band (10) nach Anspruch 1, wobei die meisten der hervorstehenden Fasern (22) an den
Wurzeln gebogen sind, wobei mindestens ein Teil der hervorstehenden Abschnitte im
Wesentlichen parallel zu der Kontaktfläche und dieser sehr nahe liegt oder diese berührt.
17. Band (10) nach Anspruch 16, wobei mindestens einige der gebogenen hervorstehenden
Fasern (22) einen im Wesentlichen aufrechten Abschnitt am freien Ende aufweisen.
1. Courroie de transmission de puissance (10) comprenant un élément de traction (14),
un corps de courroie élastomère (18) ayant une pluralité de fibres discontinues déformables
(22) incorporées à l'intérieur, et une surface de contact de poulie (20) ;
avec chaque dite fibre (22) ayant un diamètre moyen initial de fibre et ayant une
forme en coupe transversale initiale qui est sensiblement inchangée pour les parties
incorporées de la fibre (22) ; et
avec une pluralité d'extrémités de fibre (24) en saillie sensiblement dressées depuis
ladite surface de contact (20) et sensiblement droites ou légèrement courbées et ayant
une longueur en saillie, et caractérisées en ce qu'elles ont une forme en saillie en coupe transversale qui est déformée de façon sensiblement
uniforme par rapport à la forme en coupe transversale initiale sur la plus grande
partie de la longueur en saillie, se soldant par des fibres en saillie de section
transversale uniforme sur toute la longueur en saillie.
2. Courroie (10) selon la revendication 1 dans laquelle la forme initiale est sensiblement
ronde et la pluralité d'extrémités de fibre en saillie (24) est déformée par rapport
à la forme ronde en une forme en coupe transversale ovale, et/ou réniforme, et/ou
oblongue, et/ou semi-circulaire, et/ou en cercle aplati.
3. Courroie (10) selon la revendication 1 dans laquelle la forme initiale est ovale ou
en forme d'haltère et la forme en saillie en coupe transversale est déformée en une
forme ovale ou en forme d'haltère aplatie ou plus allongée.
4. Courroie (10) selon la revendication 1 dans laquelle les fibres discontinues (22)
ont une longueur moyenne d'environ 0,5 à environ 5 mm, et un diamètre moyen initial
d'environ 10 µm à environ 50 µm.
5. Courroie (10) selon la revendication 1 dans laquelle les fibres discontinues (22)
ont une longueur moyenne d'environ 1 mm à environ 3 mm, et un diamètre moyen initial
d'environ 20 µm à environ 30 µm.
6. Courroie (10) selon la revendication 1 dans laquelle ladite longueur en saillie représente
au moins 2 diamètres moyens initiaux de fibre.
7. Courroie (10) selon la revendication 1 dans laquelle ladite longueur en saillie représente
environ 5 à environ 20 diamètres de fibre.
8. Courroie (10) selon la revendication 1 dans laquelle ladite fibre déformable (22)
est une ou plusieurs fibres choisies dans le groupe constitué par un nylon-6, un nylon-46,
un nylon-66, un acrylique, un polyester, une polycétone, une polyoléfine, et un méta-aramide.
9. Courroie (10) selon la revendication 1 dans laquelle la fibre déformable (22) a un
point de ramollissement supérieur à environ 100 °C.
10. Courroie (10) selon la revendication 1 dans laquelle ladite fibre déformable (22)
est du nylon ou du méta-aramide.
11. Courroie (10) selon la revendication 1 dans laquelle ladite déformation de fibre est
caractérisée par un rapport entre une dimension principale et une dimension secondaire dans la gamme
d'environ 1,2 à environ 5, ou caractérisée par une déformation par rapport à la circularité d'un facteur d'environ 1,33 et 0,67
pour les deux axes, respectivement.
12. Courroie (10) selon la revendication 1 dans laquelle ladite déformation de fibre est
caractérisée par une dimension principale qui est allongée d'environ 10 % à environ 100 %.
13. Courroie (10) selon la revendication 1 dans laquelle la rugosité de surface moyenne
de la surface de contact (20) est supérieure à environ 20 µm et irrégulière.
14. Courroie (10) selon la revendication 1 dans laquelle la quantité de ladite fibre (22)
dans ledit corps de courroie élastomère (18) est d'environ 1-50 phr pour 100 parties
d'élastomère.
15. Courroie (10) selon la revendication 1 dans laquelle le nombre de fibres exposées
(22) sur la surface de contact (20) se situe dans la gamme de 20 à 150 fibres par
mm2.
16. Courroie (10) selon la revendication 1 dans laquelle la plupart des fibres en saillie
(22) sont pliées au niveau des racines avec au moins une portion des parties en saillie
sensiblement parallèle à et très proche de ou touchant la surface de contact.
17. Courroie (10) selon la revendication 16 dans laquelle au moins certaines des fibres
en saillie pliées (22) ont une portion sensiblement dressée à l'extrémité libre.